171 services carry this tag in their source record. Tags come from the provider, not from us — a tag is a claim about what the service does, not proof that it does it well.
Fetch any public URL and report whether its HTTP 402 challenge is a schema-valid x402 v2 PaymentRequired, payable in Base USDC, and catalog-ready (bazaar discovery declaration + facilitator support).
Use when an agent must choose which marketplace to spend effort in: how crowded is it (bids per job, measured), and does money actually move here (payer share, buyer behaviour, freshness)? Answered with coverage and as_o...
Base or Ethereum contract address -> ABI and function list: Sourcify verification (exact/partial match), contract name, compiler, ABI, function selectors + signatures, event topics; proxies (EIP-1967, ZeppelinOS, others...